Dual purpose extractor assembly for machine guns



April 26, 1966 WALLACE 3,247,610

DUAL PURPOSE EXTRAGTOR ASSEMBLY FOR MACHINE GUNS Filed March 30, 1965INVENTOR Juhn lVLWnllm: E

ATTORN EYS Patented Apr. 26, 1966 3,247,610 DUAL PURPOSE EXTRACTORASSEMBLY FOR MACHINE GUNS John M. Wallace, Indian Orchard, Mass.,assignor to the United States of America as represented by the Secretaryof the Army Filed Mar. 30, 1965, Ser. No. 444,089

Claims. (Cl. 42-25) The invention described herein may be manufacturedand used by or for the Government for governmental purposes without thepayment to me of any royalty thereon.

This invention relates to machine guns and pertains more particularly tothe cartridge extractor devices therefor.

One of the troublesome problems encountered in the design of mostmodern-type machine gunsis the conservation of space and weight whichrequires that the components be reduced to a minimum and that they :beas compactly arranged as possible. In some machine guns, such as theXM140 30 mm. Automatic Gun, the feed pawls are designed for reversibleinstallation to changethe direction of feed. This reversal requires theremovel of a sliding pawl stop plate, which is located over thecartridge extractor assembly, giving rise to problems as to the designof the extractor assembly and the means for releasably retaining thepawl stop plate in installed position.

These problems have been overcome and compactness of design achieved bythis invention which provides an extractor assembly that also serves toreleasably lock the pawl stop plate in installed position and in whichthe parts are all interlocked together so as to remain assembled whenthe pawl stop plate is removed for reversal of the feed pawls.

The specific nature of the invention as well as other objects andadvantages thereof will clearly appear from a description of a preferredembodimentas shown in the accompanying drawings in which:

FIG. 1 is a fragmentary, longitudinally cross-section view showing theextractor assembly of this invention installed in a gun with a cartridgelocated at the firing station and the barrel in battery position;

FIG. 2 is a view taken along line 22 of FIG. 1;

FIG. 3 is a further fragmentary view similar to FIG. 2 but shows the capof the extractor assembly depressed for release of the pawl stop plate;

FIG. 4 is a view similar to FIG. 3 but shows how the interlocking of theparts of the extractor assembly prevents disassembly thereof when thepawl stop plate is removed; and

FIG. 5 is an exploded view of the extractor assembly.

Shown in the figures is an automatic gun 12 having a receiver 14 with anintegral breechblock 16 and a barrel 18 which is reciprocal between aforward loading position and a rearward battery position. Gun 12 isadapted for firing a cartridge 20 having a case 22 with an extractorgroove 24, which cartridge is linked to others thereof and is fedsideways to a firing station, noted at xx, in receiver 14. feeding iseffected by a feeding mechanism having a feed pawl device (not shown)which is reversibly mounted in receiver 14 for changing the direction offeed. The reversal of the feed pawl device (not shown) requires theremoval of pawl stop plate 26 which is slidingly mounted in the top ofreceiver 14 by T-slot means 28 and which is located in the-receiver overthe firing station.

Pawl stop plate 26 is releasably locked in assembled position and case22'is held back when barrel 18 is actuated forwardly, for extractiontherefrom, by an extractor assembly 30 which is mounted in a verticalbore 32 through the top of receiver 14. Bore 32 is counterbored at 34from the ,top of receiver 14, under pawl stop plate 26, to a ledge 36.

Extractor assembly 30 includes an extractor 38 having a bar 40 and acylindrical shaft 42 which extends integrally from the bar intermediatethe ends thereof and is received by bore 32 and counterbore 34. Shaft 42includes a large diameter portion 44 which has a diameter similar tothat of bore 32 and a coaxial, reduced diameter portion 46 which extendsaxially from a shoulder 48 so as to be received by counterbore 34. Abutton 50 is formed on the free end of reduced diameter portion 46. Bar40 is provided with a vertical rib 52 at each end and such ribs havesliding contact with a front face 54 of breechblock 16 to preventrotation of extractor 38 around the axis of shaft 42. Formed along thebottom of bar 40 is a lip 56 which is engageable by extractor groove 24of case 22 during displacement thereof to and from the firing station.An arcuate recess 58 having a radius similar to the inside radius ofextractor groove 24 is formed in lip 56 so that the extractor groove ofcartridge 20 is in full engagement with the recess, to increase the areaof engagement of case 22 and extractor 38, whenthe cartridge is in thefiring station.

Extractor 38 is resiliently mounted :by means of a compressible spring60 coiled around reduced diameter portion 46 within counterbore 34. Thebottom end of spring 60 seats on a washer 62 which is slidingly mountedon reduced diameter portion 46 and which has an inside diameter similarto that of such reduced diameter portion. The top end of spring 60contacts a cap 64 replaceably mounted on the free end of shaft 42 ashereinafter described.

Cap 64 is cylindrical in configuration and is provided with an annularflange 66 around the bottom end. The outside diameter of flange 66 issimilar to the diameter of counterbore 34 so as tobe slidingly receivedthereby. A knob 68, which is formed above flange 66, is receivable by amating hole 70 in pawl stop plate 26 when such plate is in the assembledposition to releasably hold the pawl stop plate therein. Formed cap 64is a cylindrical charnber 72 which extends between a top end 74 thereofand an internal flange 76 which forms a shoulder 78 and a cylindricalaperture 80. Chamber '72 has a diameter similar to that of button 50 andaperture 80 has a diameter similar to that of reduced diameter portion46. Button 50 and reduced diameter portion 46 are insertable sidewaysinto chamber 72- and aperture 80, respectively, by means of a T-shapedopening 82. As shown in FIG. 3, end 74 and shoulder 78 are spaced sothat cap 64 may be displaced sufficiently on shaft 42, for knob 68 toclear hole 70, when the cap is manually depressed by an instrument suchas shown at 84. Cap 64 is assembled on and disassembled from shaft 46 bypressing upward ly on bar 40 until it contacts the top of receiver 14,whereupon button 50 is spaced sufficiently above the top of the'receiver so that the cap may be slipped over the button ward positionwhen the upward pressure against the extractor is removed.

OPERATION Extractor assembly 30 is assembled to receiver 14 by insertingshaft 42 upwardly into bore 32 from the inside of the receiver and thendropping first washer 62 and then spring 64 down into counterbore 34 andover reduced diameter position 46. Holding extractor 38 up so that bar4t contacts the top of receiver 14, cap 64 is then slipped slidewaysonto shaft 42 with button 50 being received by chamber 72. With pawlstop plate 26 installed, extractor 38 has limited vertical movementbetween contacts of cap 64 with end 74 and the top of flange 66. Also,when pawl stop plate 26 is installed and locked in position, the forceof spring at is directed against extractor 38, which is biased therebyto its lowest position, as the upward displacement of cap 64 by thespring is blocked through the contact of shoulder '73 with the bottom ofpawl stop plate 26.

As cartridge 20 is moved to the firing station during feeding, extractorgroove 24 of the cartridge contacts the adjacent end of lip 56, wherebyextractor 38 is raised as the end of the lip rides up on top of thecase. When the incoming cartridge 29 approaches the firing station,extractor 38 is biased downwardly by the pressure applied by spring 61through washer 62 to shoulder 48 as ex tractor groove 24 comes inregistry with recess 58, to assure the engagement of the extractor withcase 22. After the firing station cartridge 29 is discharged, case 22 isheld back by extractor 38 as barrel 18 is forwardly displaced by anoperating mechanism (not shown) so as to be extracted from the barrel.After extraction, fired case 22 is moved sideways from the firingstation with extractor 33 being raised against the bias of spring 60 asthe case moves out of registry with recess 5%.

To remove pawl stop plate 25 for reversing the feed pawl device (notshown), an instrument, such as shown at 84, is pressed against the topof knob 68 through hole 70, depressing cap 64 until the knob is clear ofthe hole. Thus, pawl stop plate 26 is free to he slid from receiver 14and the feed pawl device (not shown) is thereby freed for removal andreversal. When pawl stop plate 26 is reinstalled, knob 68 snaps up intohole 70 when in registry therewith. As is shown in FIG. 4, when pawlstop plate 26 is removed, extractor assembly 3th remains in assembledcondition as cap 64 is retained in assembled position on shaft 42,through the engagement of counterbore 34 with flange 66 and thereby thecap cannot be slid sideways from shaft 42. Flange 66 is held incounterbore 34, when pawl stop plate v26 is removed, through the weightof extractor 38.

Although a particular embodiment of the invention has been described indetail herein, it is evident that many variations may be devised withinthe spirit and scope thereof and the following claims are intended toinclude such variations.

I claim:

1. In a machine gun for firing a cartridge having a case with anextractor groove and including a barrel and a receiver with a firingstation and a breechblock, the combination including a member slidinglymounted in the receiver adjacent the firing station, and an extractorassembly including means for releasably locking said member in aninstalled position and means for engaging the extractor groove of thecase when in the firing station for extracting the case from the barrelincluding an extractor provided with a shaft slidingly mounted in acooperating bore in the receiver, a bar integral with said shaft anddisposed for sliding contact with a front face of the breechblock, a lipengageable with the extractor groove when the case is moved sideways tothe firing station and an arcuate recess having the same radius as theinside diameter of the extractor groove formed in said lip forengagement with the extractor groove when the case is in the firingstation.

2. In a machine gun for firing a cartridge having a case with anextractor groove and including a barrel and a receiver with a firingstation and a breechblock, the combination including a member slidinglymounted in the receiver adjacent the firing station, and an extractorassembly including means for releasably locking said member in aninstalled position and means for engaging the extractor groove of thecase when in the firing station for extracting the case from the barrel,said means for engaging the extractor groove including an extractor, andsaid means for releasably locking said member including a cap mountedfor limited displacement on said extractor, a knob on said capreceivable by a mating hole in said member for releasably locking saidmember in the installed position, and a spring mounted on said extractorso as to press against said cap to releasably hold said knob in saidhole.

3. The combination as defined in claim 2 wherein said extractor includesa bar with a lip engageable with the extractor groove when the case isin the firing station, a shaft extending from said bar, and means onsaid shaft disposed in' cooperation with said cap for limiting relativedisplacement thereof to that sufficient for pressing said knob from thehole and for preventing axial removal of said cap from said shaft.

4. The combination as defined in claim 3 wherein said spring is ofcoiled compressible type and is coiled around said shaft for contact atone end with said cap, and including a shoulder on said shaft, a washerslidably mounted on said shaft between said spring and said shoulder fortransferring the force of said spring to said extractor when said knobis received by said hole in said member to resiliently press theextractor against the engaged extractor groove.

5. The combination as defined in claim 3 wherein said means on saidshaft includes a button formed on the end thereof, and wherein said capis provided with a chamber for receiving said button, an end of saidchamber and a flange spaced therefrom in said chamber to limit thedisplacement of said cap on said shaft and prevent axial removaltherefrom, and T-shaped opening permitting entrance of said cap onlysideways into said chamber.-

References Cited by the Examiner UNITED STATES PATENTS 2/1905 Bennett42-25 4/1940 Garand 4225 References Cited by the Applicant UNITED STATESPATENTS 5/1963 Raleigh.

1. IN A MACHINE GUN FOR FIRING A CARTRIDGE HAVING A CASE WITH ANEXTRACTOR GROOVE AND INCLUDING A BARREL AND A RECEIVER WITH A FIRINGSTATION AND A BREECHBLOCK, THE COMBINATION INCLUDING A MEMBER SLIDINGLYMOUNTED IN THE RECEIVER ADJACENT THE FIRING STATION, AND AN EXTRACTORASSEMBLY INCLUDING MEANS FOR RELEASABLY LOCKING SAID MEMBER IN ANINSTALLED POSITION AND MEANS FOR ENGAGING THE EXTRACTOR GROOVE OF THECASE WHEN IN THE FIRING STATION FOR EXTRACTING THE CASE FROM THE BARRELINCLUDING AN EXTRACTOR PROVIDED WITH A SHAFT SLIDINGLY MOUNTED IN ACOOPERATING BORE IN THE RECEIVER, A BAR INTEGRAL WITH SAID SHAFT ANDDISPOSED FOR SLIDING CONTACT WITH A FRONT FACE OF THE BREECHBLOCK, A LIPENGAGEABLE WITH THE EXTRACTOR GROOVE WHEN THE CASE IS MOVED SIDEWAYS TOTHE FIRING STATION AND AN ARCUATE RECESS HAVING THE SAME RADIUS AS THEINSIDE DIAMETER OF THE EXTRACTOR GROOVE FORMED IN SAID LIP FORENGAGEMENT WITH THE EXTRACTOR GROOVE WHEN THE CASE IS IN THE FIRINGSTATION.